Sandwich enzyme immunoassay of human chorionic gonadotropin using polystyrene beads as solid support

Abstract

A solid-phase sandwich enzyme immunoassay for human chorionic gonadotropin (hCG) employing monoclonal antibodies directed against β- and α-subunits is described. Polystyrene beads used as solid support were coated with monoclonal anti-β-hCG antibody. Monoclonal anti-α-hCG antibody was labelled with the enzyme, horseradish peroxidase. The assay could be performed by a "one-step" or "two-step" procedure. The sensitivity of the two-step procedure was 7.8 ng hCG/ml with a linear range up to 500 ng hCG/ml. The one-step procedure had a measurement range between 15.6 and 125 ng hCG/ml. Within the limits of measuring ranges, the two procedures had similar accuracy, the correlation coefficient being 0.987. Twenty-one urine samples from pregnant women were analysed by the two-step procedure and also by radioimmunoassay. The results were comparable, with r=0.956.